Tex. Util. Code § 52.110
(a) In a proceeding before the commission in which it is alleged that a telecommunications utility engaged in conduct in violation of Section 52.107, 52.108, 52.109, or 52.112, the burden of proof is on:
(2) except as provided by Subsection (b), the responding telecommunications utility if the proceedings are:
Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. Sept. 1, 1997.
Amended by Acts 1999, 76th Leg., ch. 1212, Sec. 11, eff. Sept. 1, 1999.